In this Blog we will cover a simple example to illustrate how CDS view associations translates to OData service associations.
The advantage of associations in CDS views is that the data is provided/join is executed only when needed also known as Join on Demand. By default, left outer join is executed at runtime when a field from the associated table is used/called. However, other join conditions can be specified as well. For example, in the CDS view below, only when a field from table ZTB_MAT_TAB is used, only then the left outer join between MARA and this table is executed and data is made available –
This same concept is applicable when using associations in OData services, by using associations in CDS views and using annotation OData.publish: true, all settings needed otherwise in SEGW can be avoided, the system automatically takes care of it.
Create a CDS view similar to the one above with the fields needed for your business case. Register it in /IWBEP/MAINT_SERVICE.
You can now test the association in SAP Gateway client using similar URI
Getting All Materials -
/sap/opu/odata/sap/ZI_MAT_TAB_CDS/ZI_MAT_TAB$format=json
Getting details from ZTB_MAT_TAB above for a single material(Association call) -
/sap/opu/odata/sap/ZI_MAT_TAB_CDS/ZI_MAT_TAB(SKU=’ABCD’)/to_MATTAB?$format=json
This example is a very simple one, however, you could have a number of fields displayed, say for example all/many Purchase order header fields. On click of details of a purchase order, all line items can be displayed using the association call similar to the URI above enabling join on demand with no additional programming.
The advantage of associations in CDS views is that the data is provided/join is executed only when needed also known as Join on Demand. By default, left outer join is executed at runtime when a field from the associated table is used/called. However, other join conditions can be specified as well. For example, in the CDS view below, only when a field from table ZTB_MAT_TAB is used, only then the left outer join between MARA and this table is executed and data is made available –
This same concept is applicable when using associations in OData services, by using associations in CDS views and using annotation OData.publish: true, all settings needed otherwise in SEGW can be avoided, the system automatically takes care of it.
Create a CDS view similar to the one above with the fields needed for your business case. Register it in /IWBEP/MAINT_SERVICE.
You can now test the association in SAP Gateway client using similar URI
Getting All Materials -
/sap/opu/odata/sap/ZI_MAT_TAB_CDS/ZI_MAT_TAB$format=json
Getting details from ZTB_MAT_TAB above for a single material(Association call) -
/sap/opu/odata/sap/ZI_MAT_TAB_CDS/ZI_MAT_TAB(SKU=’ABCD’)/to_MATTAB?$format=json
This example is a very simple one, however, you could have a number of fields displayed, say for example all/many Purchase order header fields. On click of details of a purchase order, all line items can be displayed using the association call similar to the URI above enabling join on demand with no additional programming.
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